


sequentially; or, what we add up to in the end

by themorninglark



Category: Free!
Genre: Fibonacci sequence, Future Fic, M/M, math dorkery
Language: English
Status: Completed
Published: 2015-05-26
Updated: 2015-05-26
Packaged: 2018-04-01 10:44:20
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,200
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4016761
Author URL: https://archiveofourown.org/users/themorninglark/pseuds/themorninglark
Summary: <blockquote class="userstuff">
              <p>This is the sum of Matsuoka Rin and Ryugazaki Rei, starting from one and one.</p>
            </blockquote>





	sequentially; or, what we add up to in the end

**Author's Note:**

  * For [buttface](https://archiveofourown.org/users/buttface/gifts).



> This goes out to one of my absolute favourite people in the entire fandom and possibly the world, my scientifically-proven destined BFF.
> 
> Happy birthday buttface, ilu ♥ I hope you enjoy this as much as I loved writing it, my first foray into this fascinating ship :D
> 
> (Also, Fibonacci numbers are super awesome, and I got... really fixated on the idea of unpacking Rinrei like this, like a Matryoshka doll? Layers stacking inside and outside of each other and adding up to something at the end. Anyway, uh, MATH! Yay.)

**_1_ **

Sweet.

 

**_1_ **

Sharp.

 

**_2_ **

_Too_ sweet.

 

**_3_ **

He swims butterfly.

 

**_5_ **

He wonders how he's doing.

 

**_8_ **

There's an inexplicable vacancy to his evenings, sometimes.

 

**_13_ **

He feels that phantom sensation on his fingertips, hands holding up taut muscle.

 

**_21_ **

He swims butterfly, and when his pulse is pounding, he tries other strokes.

He remembers raw power. Strength. Words of guidance.

 

**_34_ **

He wonders how he's doing, his awkward _speedo megane_. He still has that text. _Rin-san, I want to swim better. Will you help me, please?_

Asking for help has never been Rin's strong suit.

 

**_55_ **

_Beauty is in the eye of the beholder._

Such a platitude, but if there's one thing swimming has taught Rei, it's the objectivity of timing his strokes to his breaths, of staying balanced over his hips, the science of _moving_ through the water, and after all that, the subjectivity of the picture that it makes.

 

**_89_ **

He feels it pricking his skin. His knuckles tingle, and he lies back, lifting a hand, staring at the shape it makes in the dim moonlight.

He flexes his fingers, stretches them out. Pretends he's reaching for a wall.

It never took him much to guide Rei in the water. The slightest nudge, and he'd understand, he'd move _just_ right.

Rin is a sensory creature. He trusts his eyes, and the movements of his muscles. He trusts his body. He trusts the numbers on the clock. So does Rei.

 

**_144_ **

When he watches Rin swim, there is a sense of _rightness_ that settles over him, quiet and intense as the nights they used to spend together.

His mind calculates the precise angle of that dive, sharp and true; sees the axis of Rin's upper body straight down the middle as his arms describe an arc through the air, counts the perfectly timed kicks to the millisecond.

It is the _rightness_ of alignment, of observing all he's been taught, put into action. Rin was a good teacher. _Is. A good teacher._ A good mentor. The kind of captain that Rei wonders if he can be, one day.

His mind rehearses theories to the letter, fits all the pieces together like a jigsaw, layer by layer, over Rin's swimming form.

His heart watches the white foam fly, asks questions with no textbook answer, and goes silent.

 

**_233_ **

Competitions abroad means new sights to see, and sharing a hotel room with a teammate.

He flashes himself a smile in the mirror, experimentally; closes his mouth and hides the points of his canines.

He's all angles and sharp edges, for someone who craves _touch_ the way he does, not with a gentle tenderness but with ferocity that consumes (and he never intends to hurt, ever, but sometimes, he can't help the feeling that he's leaving scratches and scrapes along the way when he brushes past others).

Touch, and warmth that blossoms beneath his skin. Rin isn't good with cold weather.

He tightens his scarf, buttons up his coat, and slings his bag across his body.

"You're overdressed," remarks Haru, emerging from the bathroom.

"Shut up," says Rin. "You're a cold-blooded freak. Some of us like to be warm."

"It's only autumn," Haru says.

Rin rolls his eyes, and flicks Haru lightly on the shoulder. Haru doesn't flinch, merely smiles.

Touch, to assure him that he is solid and wanted and _here_ , that there is a place for him in this world, among the people he's accidentally bumped into, while stumbling through years of life. People who became his friends. People who might even - if the equations work out - love him.

Touch, to assure him he is no spectre himself.

And if he falls, at least he's no stranger to getting up again.

 

**_377_ **

Under the glaring lights of a stadium in Osaka, he snaps a picture and sends it off.

_Rin-san, I thought you might like to see this._

He puts his phone into his pocket, and watches as the members of the Samezuka medley relay team, led by Nitori Aiichirou, cheer and clap each other on the back at the poolside. They're not huggers, this lot.

And Rei's photographic memory flashes back to a year ago, remembers that when Rin punched the air in triumph, climbed out of the pool after Samezuka's victory, he'd high-fived his teammates, stood with a hand on his hip and smiled.

He had not hugged them then, not the way he'd hugged Haruka and the others.

He hears footsteps coming up softly next to him. "What are you thinking about, Rei-chan?"

Rei turns. He smiles at Nagisa. "Nothing, Nagisa-kun. I just thought… Rin-san would be really proud of his team if he could see them now."

"Mmm." Nagisa nods. "I think you're right…"

Rei's fingers tighten round the railing at the bleachers, knuckles turning white. The relay swimmers are shuffling off now into the locker rooms. They're getting the pool ready for the next race.

His pocket buzzes, startling him, and he reaches for his phone.

He hadn't expected a reply, now, if ever; it's evening time in Australia and surely, surely, Rei thought, Rin would be busy with friends, busy working, busy -

Rin never stops moving forward.

 _New Message_  
_From: Matsuoka Rin  
_ _Hey, thanks for thinking of me. That's awesome. What about you guys? How was it?_

His fingertips hover over the keypad.

_We tried our best. It wasn't good enough, though._

The reply comes almost instantly.

_Bullshit. You're the captain, aren't you? How do you think your team would feel if you told them their best isn't good enough?_

Rei swallows, and stares down at his screen. He sees Rin crossing his arms and staring straight at him, speaking those words from across an ocean. His voice isn't raised. He says this like he's stating a theoretical truth, he says it quietly, directly, and it's more powerful than yelling.

And Rei thinks about how Rin saves his hugs for the imperfect moments, the moments when he's cracked open and clenching at his chest.

 

**_610_ **

"You know, Rei - "

Rin pauses, midway through his sentence. He stuffs his hands in his pockets, and stares out at the calm blue waters of the Pacific, an old childhood habit for when he's lost for words.

Rin isn't like Makoto. He doesn't always know _exactly_ what to say, every time. But he isn't Haru, either; rarely, if ever, does he find himself _completely_ tongue-tied. It is a frustrating sensation. He wonders how Haru lives with it.

The words burn a hole at the back of his throat. Rin's words. Direct and blunt. _If you're not careful, you might get bitten._

Rei turns, looking politely perplexed. "Rin-san?"

"Seriously, drop the _-san_ already. It's too formal. We're past that," says Rin irritably, running a hand through his hair. The breeze from the ocean is chilly today. He notices Rei shiver slightly, next to him, and takes a step back, away from the wind.

Rei looks away. He doesn't say anything at first, just nods, a little awkward, a little too poised.

"I think I'll stay here for another year. After I graduate," says Rin.

Rei's head turns, sharply, and his eyes widen.

"I thought you would come back," he says. "To train with the national team - "

Rin breathes in the salt of the sea air, lets out a small breath. "I thought so too. But I think… I think my coach here still has more to teach me. I can't explain it, Rei, I just _feel_ like my time here isn't done yet."

Rei is silent for a while. Rin shoots him a look, sees the gears turning in his head as he keeps his gaze fixed firmly on Rin, brow furrowed behind those red-framed glasses. He'd thought red was a bit odd, a bit showy for someone like this guy, when they first met; now, he knows better.

"Have you told Haruka-senpai yet?" asks Rei.

"No," says Rin. "I haven't told anyone else yet. I don't know what Haru would say. Or Makoto."

"I think they would understand."

"Yeah," says Rin. "And even if they didn't, they'd try to, for me."

Standing in one spot makes Rin feel restless. He kicks the sand at his feet, and watches the specks fly up around his shoes in dusty clouds.

"But," Rin adds, raising his voice as he looks at Rei, "I wanted to tell you first."

" _What?_ Me?" Rei sputters.

"Yeah. Because, well, something like this, I _know_ you'll get me. Don't you feel it too, Rei?"

Rin's fingers curl in his pockets, form tightly-balled fists as the muscles on his arms tense up, all the way to his shoulders.

"That feeling, like you _want_ to improve, you want it so fucking bad. You feel like you have so much more to learn. You don't want to give up. You're reaching out - your fingers are _almost_ touching it, you're so close - "

"Yes," says Rei, quietly, cutting Rin off.

"Yes," says Rei, and there's an intensity to his voice that resonates with the deepest part of Rin.

Rin turns his gaze out towards the horizon, and thinks of swimming to reach it.

"If it's you, I know you can do it," says Rei, fiercely.

"Hell yeah," says Rin.

Rei shoots him an answering grin.

"I'll keep trying too, Rin-san - _Rin_. I'll work hard - "

"Idiot," says Rin, and reaches out to swat Rei on the arm. "I know you bloody well will. Or you wouldn't be _you_."

And as Rin watches the determined set to Rei's mouth, the firm line it makes, he ponders the sum total of the _you_ of Ryugazaki Rei.

This is not the first time he has contemplated this.

 

**_987_ **

Today, he eschews his lab coat for a freshly pressed suit. His jacket is black, and his tie, a gift from Nagisa, is a vivid violet that really sets off his eyes.

He makes his way to the university by his usual route, on the metro. His colleague had offered to swing by and pick him up; Rei had declined the offer, politely. He's always liked the metro. He likes the low, rhythmic hum of the train, the sense of steady movement beneath his feet. The train comes on a schedule, at fixed intervals. It is dependable and constant. It is logic incarnate.

And every time he rides it, he's reminded of taking the train to school in Iwatobi.

_I'm growing nostalgic already… surely I'm too young for that._

The stray, rueful thought passes through Rei's mind, as he gazes out of the window at Tokyo's skyline.

Rei has grown used to Tokyo, fond of it, in his own way. Haruka is based here, and they keep in touch. He has friends. He has work to plunge himself into. Work he is proud of.

He has new glasses now, sensible black-framed ones that seemed more fitting for his position when he bought them on the spur of the moment.

(He still keeps the red pair, neatly folded in their original case.)

It's a fine summer day, no breeze in the air. The courtyard smells of freshly cut grass.

 _Click, click,_ the heels of Rei's perfectly polished shoes ring out, as he walks briskly down the gravelled path towards the library in the Science wing, where they have cordoned off a private room with wine and canapes.

He shakes a lot of hands, says _you're too kind_ a lot, and brushes compliments off with finesse. His eyes scour the crowd, ceaselessly.

He is called on to make a short speech impromptu. He obliges, with a sheepish laugh and some brief words about his book. He expresses his thanks towards his ever patient colleagues and advisors. He bows deeply. He is grateful.

He straightens to warm applause, and then -

_There it is._

A telltale white and sky blue jacket hovering near the back. The face in the shadows is hidden from sight.

Rei smiles anyway. He heads over, pausing to pick up two glasses of fruit punch.

The figure stands, unmoving, for a few minutes as Rei approaches, starts to call out, "Haruka - "

The figure stirs.

Puts his hands in his pockets, fidgets, traces an arc on the ground with the toe of his shoe.

Rei's voice catches, and chokes.

_That's not Haruka. Haruka doesn't - move - like that - that's -_

"Yo," Rei hears, and the voice is scratchy, parched, but familiar, _so_ familiar. "I'm glad you come bearing drinks. I'm fucking thirsty."

"Rin," says Rei, staring.

He takes a step forward, but Rin's already crossed the distance between them with a few long strides, taken a glass out of Rei's hand and swigged down a long gulp. He makes a face. "Too sweet."

"You're back," says Rei.

Rin nods. "Uh-huh."

"You're wearing Haruka-san's jacket."

Rin looks down at himself. "Oh, yeah. I'm dressed for, like, _summer_ , right? I've only got this sleeveless tee on, and Haru said, _Idiot, Rin, you can't go into a fancy function like that, take my jacket._ "

"Haruka-san is here too?"

"Yeah, he's hanging outside."

Rin pauses. "I think he figured, I ought to come say hi to you," he adds. "It's been a while, huh?"

Rei nods. He barely trusts himself to speak. "Y-yes… it has."

He feels his drink melt in his hand, takes a quick sip to stall. (It doesn't taste too sweet to him.)

"Ah, don't look so surprised. Hell, I - I've missed out a lot over the years, you know? I didn't want to miss this."

Rin's sharp grin softens, dissolves into a sigh and a smile.

"You've worked hard, Rei," he says, simply.

And for the first time, after all the congratulations he's received - after all the peer reviews, the pithy headlines - _youngest Doctor at university publishes first book_ -

For the first time, looking at the pride shining on Rin's face, Rei feels a lump well up in his throat, and he blinks.

He is seventeen again. He is graceless and gangly. His butterfly's just passable, and he can't swim any other strokes in a straight line. But there is Rin by his side in the pool, holding him up, and then letting him go because he has _faith_ , and telling him -

_You've worked hard, Rei._

"Well - "

And Rei smiles.

"The next book will be even better."

Rin looks startled for a split second, before that grin returns to his face.

"Yeah," he says. "Now _there's_ the Rei I know and love."

And he says this so easily, casually, the word slipping out of his lips just like that.

Rei feels a blush starting up his neck. He coughs.

"How long are you staying this time?" he asks.

"Well…" says Rin, thoughtfully, holding his gaze, "I think… for good."

Rei opens his mouth to ask why. He takes a breath.

Rin taps his fingers on the side of his glass, eyeing Rei steadily.

The question dies on the tip of Rei's tongue. It fades, into a stammered _hmm_.

It's not beautiful at all, thinks Rei, this gaping awkwardness, but Rin's already seen the _ugliest_ of him, and he's still here, he's still flown nearly 5,000 miles to be standing _here_ , right now -

"Oh, stop gawking," Rin snaps, suddenly. "It's embarrassing."

And he leans forward.

They are exactly the same height, the two of them; and finally, it is _this_ that all their insecurities and their striving add up to in the end, and they fit together with a mathematical precision that is innately pleasing to Rei, even as the kiss that brushes his lips makes all thoughts of numbers fly right out of his head, for once in his life.

 

**_1,597_ **

" _Tadaima_."

Rin looks up, startled. "Oh, Rei - _okaeri_ , I didn't hear you come in."

"You were really engrossed," says Rei, taking off his shoes and jacket. "What are you reading?"

Rin picks up the card on the coffee table and throws it at Rei like a Frisbee. "Check it out."

Rei plucks it out of the air (Rin notes, with approval, that his athletic agility hasn't left him) and scans it quickly, eyebrows raised. "An invitation to the Samezuka Academy Cultural Festival?"

"Yeah. Came in today's mail."

"Really. Why?"

Rei walks over to the couch where Rin is sprawled, shoves his feet off the armrest and perches there, giving Rin a token smack on the ankle when he simply stretches his legs back out onto Rei's lap and wiggles his toes.

"Because this." Rin waves the piece of paper he's holding, with the Samezuka crest printed in the top right hand corner. "The swim club's holding some kind of… what did they call it?"

He squints at the letter again. " _Captains' All-Star Race_."

"I see." Rei laughs. "And you're invited to participate."

"Yeah. I guess Mikoshiba will be there too. Wanna come?"

"A chance to watch you and Mikoshiba-san race?" Rei's eyes gleam as he pushes up his glasses. "Of course. I never got to watch you beat the captain…"

"You know, I don't remember if I actually did," Rin admits.

" _What?_ " Rei cries. "So… Mikoshiba-san is _unbeaten_?"

"Hey, I told you, he defies logic - "

"Oho."

"What does _Oho_ mean?"

Rei shrugs with a maddening nonchalance. "Nothing. Just that - when you graduated - someone _did_ beat you, right?"

Rin frowns. "So?"

"So if we're talking about _All-Star Captains_ …"

Rin knows one surefire way to win an argument with Rei. He doesn't use it all that often (trouncing him with _reason_ is so much more satisfactory), but tonight, Rei's hair is slightly mussed, and his shirt isn't buttoned all the way up like it usually is because it's August and it's _sweltering_ , and Rei gets _heated_ as easily as Rin does -

And tonight, the thought of taking a trip back to Iwatobi with Rei puts such a huge stupid grin on Rin's face that he'll die if he doesn't hide it by any means possible.

"…really," Rei continues, "the all-time all-star, so to speak, should be - "

Rin doesn't let Rei finish the sentence.

He's _really_ good at moving fast when he has to, and in one fluid motion, he pulls himself upright, reaches out -

Yanks Rei towards him by the half-open collar at his neck, gives him a small, tantalising lick right by his ear, where he knows Rei is particularly sensitive.

Rei's answering whimper sends a jolt shivering right through Rin's body.

Though it's not like they aren't used to fighting, about one thing or another - on and off -

 _"Remember when I died? You said you would avenge me."  
_ _"Yeah. And I totally did."  
_ _"Excuse me, it was my perfectly calculated trap that took Nagisa out!"  
_ _"Pssshh, semantics - I won the game for our team, didn't I?"  
_ _"Well, I still think I avenged myself..."_

They do not fight over whether to take the plane or the train to Iwatobi. Flying is so much more comfortable, and they both agree wholeheartedly that they _don't_ want to arrive looking like bedraggled stray cats.

They fight over where to stay. Rei insists that he doesn't feel quite _right_ , staying under the same roof as Gou-san, it's _weird_ -

"What, just because she's your friend and now you're sleeping with her brother?"

Rei sputters and chokes on his water as Rin shoots him the most lascivious of smiles, and in the end, Rin wins that argument too.

And they don't fight over where to go, first, when they arrive; it's Rei who gets changed quickly and tugs Rin towards that path to the mountains, and together they bow their heads at a lone gravestone near the shrine that overlooks the sea.

"It's my first time meeting your dad," Rei remarks, in hushed, respectful tones.

"Is it?" Rin glances over, and smiles. "I think he would have liked you."

"Y-you're just saying that," Rei stammers, flustered.

Rin loves making Rei flustered. It's one of his favourite pasttimes.

He takes Rei's hand and laces their fingers together. He does not tell Rei what, _exactly_ , his dad would have liked about him; it's not like he really has anything to go on as regards Matsuoka Toraichi's assessment of his son's boyfriends. Would he have liked Rei's drive? Brains? Sheer dumb determination? Or, Rin wonders, are these just what _Rin_ loves, projected on hazy, idealised memories of his father?

No, it's not like he can define it quite so precisely.

He just _knows_. And he knows, surer than ever when he sees Rei make a silent little bow of goodbye over his shoulder, just before they leave the mountain.

When the morning dawns, Rin has to blink a few times to remember where he is. This is not the pale sunrise of Tokyo streaming through his windows. This is a fierce, hot sun of pink and crimson, painting the sky recklessly over the sea.

This is the sunrise that Rin grew up with.

Gou offers them breakfast. She's making omelettes, and Rin has to tell her, while Rei is in the bathroom, to make Rei's non-runny because he's a _doofus_ and has a thing about uncooked egg and salmonella and _don't ask_ , it's not like Gou never knew that Rei was a huge dork -

"I knew that," says Gou, with a wry smile, "I just never knew huge dorks were your _type_ , Onii-chan."

Rin feels his face grow flushed. "You're a few years too young to sass me," he mutters.

Gou smiles sweetly.

They get to Samezuka early so Rin has time to walk around before his afternoon race, making a mandatory stop at the swim club's maid cafe, where Rei eyes the costumes with a persistent twitch of his eyelid and Rin signs a bunch of autographs.

"It's _still_ not beautiful," Rei says with a chagrined frown when they leave.

"You didn't see me in it," Rin remarks.

Rei turns traffic-light red, stops and stutters in the middle of the hallway, and Rin laughs.

He knows that nostalgia will do him in, always, and so he makes sure to swerve past the pool and the sakura trees he knows are outside; he'll see them later anyway.

He walks in the opposite direction. And it's then that they catch sight of the track and field team, setting up a hurdles demonstration.

"Ah - "

By his side, Rei lets out the tiniest of sighs, and Rin doesn't miss the way his gaze lingers with a barely veiled curiosity -

And before Rin knows it, he finds his feet moving quickly towards the buff guy barking orders.

"Hey, you," he calls out. "Are you the track captain?"

"Yeah, who - " The student turns around, and his eyes widen. "You're… you're _Matsuoka Rin_!"

Rin waves a dismissive hand in the air. "Yes, I know who I am. Listen - "

He jerks a thumb behind him, in Rei's direction.

"This guy used to be a pole vaulter. Any chance he can give it a go? For old times' sake, and all."

Rei catches up with Rin, and his mouth falls open as he catches the last of Rin's words.

"Wait, what are you saying - I can't - I haven't done it in _years_!"

"So? It's still _in you_ , Rei. I know it. Come on."

The track captain sizes Rei up, scratches his head and shrugs. "I don't know…"

"I'll sign your jacket for you," says Rin. "Or something. Your chest?"

" _Rin!_ " Rei sputters, as the captain coughs, mutters something about how that won't be necessary, and says to Rei, _just one jump_ , as he gestures to someone to go set up the pole vault.

And Rin smiles to himself as he sees the theatre of Rei's emotions play out on his face, from disbelief, to curiosity, to a naked, hopeful longing.

He turns to Rin, pushes up his glasses and asks one question, out loud.

"Why?"

"Because," Rin says, "I'm the only one who's never seen your pole vault."

Rei's eyes widen.

He takes off his jacket, hands it to Rin, stretches his arms overhead as he walks over to the far end of the track. He takes his time to warm up. Rin strolls over, keeping his distance, Rei's jacket a welcome warmth on the crook of his forearm.

Rei picks up the pole.

He doesn't look at Rin. He keeps his gaze razor sharp, dead ahead.

Rin holds his breath as Rei lets his out. Chest dipping, shoulders tensing, fingers tightening. Legs poised to spring into motion.

He starts his run-up - slowly at first, faster, _faster_ \- he flies -

And Rin, sizing up the parabola of Rei's body, realises with certainty:

 _He's gonna crash_.

That bar is right in the path of his arc.

And Rin thinks, _damn you, Rei -_

It's always been like this, with Rei, since their first meeting.

_You don't even know the fucking half of it, do you?_

He'll try. Oh, _how_ he'll try. He'll try his goddamned hardest, even if it's something he doesn't _know_ he'll succeed in, and that'll only make him try even _more_. And he'll never give up, his awkward _speedo megane_...

Not so awkward anymore. He's found a sort of grace in his imperfections, unconsciously.

And yeah, Rin never let _sappiness_ stop a thought from crossing his mind - in the end, it doesn't come down to much, just one word -

_beauty -_

And Rei's always had it.

 

* * *

 


End file.
